# Human Milk and Infant Gut Microbiome in Association With Infant Fecal Metabolome and Child Blood Pressure

## TL;DR

Breastfeeding combined with specific gut bacteria in infants may lower blood pressure in childhood.

## Contribution

Shows how human milk feeding interacts with Bifidobacterium infantis to influence infant metabolites and blood pressure.

## Key findings

- Breastfeeding lowers systolic blood pressure in children with B infantis at 3 months.
- B infantis and other microbes interact with milk feeding to affect fecal metabolites and blood pressure.
- The effect is strongest at 3 months and not observed at 1 year of age.

## Abstract

Does human milk feeding interact with infant gut microbes, particularly Bifidobacterium longum subsp infantis and other milk-degrading microbes, in association with infant fecal metabolome and childhood blood pressure?

In this cohort study of 1324 Canadian children, any human milk feeding, compared with no human milk feeding, at age 3 months was associated with lower child systolic blood pressure at ages 3 and 5 years among infants harboring B infantis at age 3 months, but not among infants who did not harbor B infantis. An interaction was also observed between human milk feeding and several other microbes at age 3 months (but not age 12 months), including other species of Bifidobacterium, in relation to child blood pressure and fecal metabolites.

These findings suggest that early-life interactions between human milk feeding and infant gut microbes may shape the infant fecal metabolome and child blood pressure.

This cohort study investigates associations of human milk feeding and infant gut microbes, including Bifidobacterium longum subsp infantis, with infant fecal metabolites and childhood systolic blood pressure.

Infant milk feeding type (eg, human milk vs formula) and infant gut microbes have each been associated with differences in microbial metabolites and childhood blood pressure; however, evidence remains limited regarding how specific infant gut microbes, at a species or strain level, in combination with milk feeding type, shape microbial metabolites and blood pressure.

To investigate whether human milk feeding and infant gut microbes, including Bifidobacterium longum subsp infantis (B infantis) and other milk-degrading microbes, are associated with infant fecal metabolites and childhood systolic blood pressure (SBP).

This cohort study was part of the Canadian Healthy Infant Longitudinal Development (CHILD) cohort study, a prospective multicenter, contemporary, population-based cohort of pregnant mothers and their offspring recruited between 2009 and 2012. Data were collected from 2009 to 2018 and analyzed from January to December 2024. Participants included a subset of children born at 35 weeks of gestation or later without congenital abnormalities or respiratory distress syndrome and with available data on gut microbiome, fecal metabolome, SBP, and covariates.

Gut microbiome, fecal metabolome, and human milk feeding status at ages 3 months and 1 year.

Age-, sex-, and height-specific SBP percentile, measured at ages 3 and 5 years.

A total of children (610 [46.1%] girls; 982 children [74.2%] delivered vaginally; mean [SD] maternal age at delivery, 33.3 [4.5] years) were included. At age 3 months, but not at age 1 year, human milk feeding and presence of B infantis showed interactive associations with infant fecal metabolites at ages 3 months and 1 year and SBP at ages 3 and 5 years. Among infants harboring B infantis at age 3 months, mixed feeding (difference, −14.81 [95% CI, −27.05 to −2.56] percentile) and exclusive human milk feeding (difference, −17.16 [95% CI, −29.48 to −4.83] percentile) were associated with a lower childhood SBP, whereas no association was observed among infants without B infantis. Several additional infant gut microbes (eg, Eggerthella lenta, Veillonella dispar) and fecal metabolites (eg, creatinine, succinic acid) also demonstrated feeding- or B infantis–dependent associations with childhood SBP.

In this cohort study, early-life interactions between human milk feeding and B infantis, among other bacteria, were associated with the infant fecal metabolome and childhood SBP, underscoring the potential importance of early-life nutrition-microbe interplay in cardiometabolic health.